Flood Potential Outlook
Issued by NWS Raleigh/Durham, NC

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FGUS72 KRAH 061625

Winter/Spring Flood Potential Outlook
National Weather Service Raleigh, NC
1115 PM EST Mon Feb 2 2017


Precipitation Summary

Precipitation was meager over central NC during the past 2 weeks,
and few locations received as much as a quarter inch of liquid water
equivalent. Temperatures have been on a "rollercoaster ride", with
daily mean temperatures ranging from as much as 15 degrees above
normal to as low as 10 degrees below normal during the 2 week period.

See www.water.weather.gov for detailed rainfall analysis.

Precipitation and departure from normal:

          Precipitation (inches) and departure from normal
            for the water year beginning 1 October 2016

    Month                RDU            GSO        Fayetteville

  October             7.10/ 3.85     3.91/ 0.78    15.07/11.81
  November            0.60/-2.52     1.02/-2.09     0.81/-1.96
  December            2.19/-0.88     1.70/-1.28     2.64/-0.01
  January             3.77/ 0.27     5.12/ 2.06     2.43/-0.87
  February (to date)  0.07/-0.49     0.03/-0.47     0.01/-0.45

Total precip         13.73/ 0.23    11.78/-1.00    20.96/8.52
Percent normal           102             92            141

                  Begin     Actual   Normal  Departure  Percent
                  date       Pcpn     Pcpn   from norm  of norm

Raleigh-Durham International Airport (RDU)

 LAST   7 DAYS   01/30/2017   0.07    0.79     -0.72        9%
 LAST  14 DAYS   01/23/2017   0.43    1.57     -1.14       27%
 LAST  30 DAYS   01/07/2017   1.66    3.42     -1.76       49%
 LAST  90 DAYS   11/08/2016   6.55    9.51     -2.96       69%
 LAST 180 DAYS   08/10/2016  18.90   20.85     -1.95       91%
 LAST 365 DAYS   02/07/2016  51.82   43.35      8.47      120%


 LAST   7 DAYS   01/30/2017   0.03    0.70     -0.67        4%
 LAST  14 DAYS   01/23/2017   0.94    1.36     -0.42       69%
 LAST  30 DAYS   01/07/2017   3.54    2.98      0.56      119%
 LAST  90 DAYS   11/08/2016   7.87    8.89     -1.02       89%
 LAST 180 DAYS   08/10/2016  15.22   19.66     -4.44       77%
 LAST 365 DAYS   02/07/2016  41.89   42.22     -0.33       99%


 LAST   7 DAYS   01/30/2017   0.01    0.72     -0.71        1%
 LAST  14 DAYS   01/23/2017   0.10    1.62     -1.52        6%
 LAST  30 DAYS   01/07/2017   1.11    3.20     -2.09       35%
 LAST  90 DAYS   11/08/2016   5.78    8.61     -2.83       67%
 LAST 180 DAYS   08/10/2016  32.62   20.58     12.04      159%
 LAST 365 DAYS   02/07/2016  54.73   44.46     10.27      123%

Streamflow and lake levels

Streamflow on streams and rivers across central NC have all fallen
due to the relative dry spell, and we now see a number of smaller,
unregulated streams across the northern tier of the area flowing
below the 10th percentile for the time of year. Flow on the Tar
river, which has headwaters across the northern tier of counties,
has shown the most marked decrease of any larger river, and flows
from Louisburg to Greenville have fallen to around the 5th

See https://waterwatch.usgs.gov for additional details.

The major water supply and flood control reservoirs in central NC
are Falls Lake and B. Everett Jordan Lake, both operated by the U.S.
Army Corps of Engineers. Falls Lake elevation is at 251.7 feet,
which is down 0.3 feet from mid January, but still a bit above its
target elevation. B. Everett Jordan Lake elevation is 216.3 feet,
down a half a foot, but also slightly above target elevation. As
such, water allocations for water supply and power generation are
100 percent at both lakes, with ~98% of flood storage available
should that capacity be needed.

See www.epec.saw.usace.army.mil for additional details.

Short term forecast

Temperatures will remain above normal over the next two weeks, with
two or perhaps three systems affecting the area which might have a
chance of producing significant precipitation. The stronger system
looks to be late next week, giving additional time for our already
low streamflows to decline further. As such, the chance of river
flooding in the short term is below normal.

Longer term precipitation outlook

We are currently in a weakening La Nina phase of the El
Nino/Southern Oscillation (ENSO) cycle. A pronounced La Nina
typically produces an increased chance for warmer and drier than
normal conditions during the winter/spring over central NC. As the
La Nina phase is expected to continue weakening and become neutral
over the next 1-2 months, the tendency towards drier conditions will
be diminishing as well. Diminished streamsflow are countered by the
weakening climatological signal favoring drier conditions. As such,
the longer range chance of river flooding is considered near normal.

Additional details and discussion may be found at the Climate
Prediction Center website: http://www.cpc.ncep.noaa.gov

In summary, current hydrologic conditions are drier than normal
across central NC. There no hints of any system in the near-term
which would be capable of producing significant rain, thus there is
a below normal chance for flooding through mid February. There are
no strong climatological signals which might point towards
prolonged wet periods in the longer range outlook. However,
given the lower confidence in this outlook, the chance of river
flooding for late February through Spring is near normal.

The next scheduled Winter/Spring flood outlook will be issued
on February 16th.

For additional hydrologic or weather information, visit our website
at www.weather.gov/raleigh.


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